Air Force Special Operations Command says it knows what failed on its CV-22B Osprey leading to crash in Japan late last year that killed eight service members. But it still does not know why the failure happened. The command says engineering, testing and analysis are ongoing to understand the cause of the material failure that led to the November 29th crash. The service is also undergoing a comprehensive review of its CV-22 program and two accident investigations into the crash are still ongoing. Hundreds of Ospreys have been grounded across the Marine Corps, Air Force and Navy since early December.